Si4840/Si4844-A10 Broadcast Analog Tuning Digital Display AM/FM/SW Radio Receiver

Si4840/Si4844-A10 Broadcast Analog Tuning Digital Display AM/FM/SW Radio Receiver
Si4840/44-A10
B R O A D C A S T A N A L O G TUN I N G D I G I TA L D IS PLAY A M/ FM / S W
R A D I O R E C E IV E R
Features








Worldwide FM band support
(64–109 MHz)
Worldwide AM band support
(504–1750 kHz)
SW band support (Si4844 only)
(2.3–28.5 MHz)
Selectable support for all AM/FM
regional bands
2-wire control interface
Mono/Stereo and valid station
indicator
Digital volume support
Bass/Treble support
Minimal BOM components with no
manual alignment
Excellent real-world performance
Automatic frequency control (AFC)
EN55020 compliant
Two AAA batteries with 2.0 to 3.6 V
supply voltage (T = 25 °C)
Wide range of ferrite loop sticks and
air loop antenna support
24-pin SSOP package
RoHS compliant








Ordering Information:
See page 20.
Pin Assignments
Applications
Table and portable radios
Stereos
 Mini/micro systems
 Boom boxes
 Clock radios
Modules for consumer electronics
Entertainment systems
 Toys, lamps, and any application
needing an AM/FM radio
 Mini HiFi
 iPhone docking




Description
The Si4840/44 is the first analog-tuned digital-display digital CMOS AM/FM/SW
radio receiver IC that integrates the complete receiver function from antenna input
to audio output. Working with Host MCU (I2C-compatible 2-wire control interface),
frequencies, and stereo/mono information can be displayed on LCD, while the
analog-tune features are kept. Leveraging Silicon Laboratories' proven and
patented digital low intermediate frequency (low-IF) receiver architecture, the
Si4840/44 deliver superior RF performance and interference rejection. The
superior control algorithm integrated in Si4840/44 provides easy and reliable
control interface while eliminating all the manual tuned external components used
in traditional solution.
Functional Block Diagram
Si484x
Si4830/34
ADC
AMI
AM
ANT
RFGND
LNA
ADC
FM
ANT
FMI
DAC
LOUT
DAC
ROUT
DSP
Si4840/44-A10 (SSOP)
LNA_EN
1
24
LOUT
IRQ
2
23
ROUT
TUNE1
3
22
DBYP
TUNE2
4
21
VDD2
BAND
5
20
VDD1
NC
6
19
XTALI
NC
7
18
XTALO
FMI
8
17
SCLK
RFGND
9
16
SDIO
NC
10
15
RST
NC
11
14
GND
AMI
12
13
GND
This product, its features, and/or its
architecture is covered by one or more of
the following patents, as well as other
patents, pending and issued, both
foreign and domestic: 7,127,217;
7,272,373;
7,272,375;
7,321,324;
7,355,476;
7,426,376;
7,471,940;
7,339,503; 7,339,504.
AGC
0/90
TUNE1/2
ADC
AFC
Rev.1.0 8/11
BAND
RST
XTAL
OSC
IRQ
REG
SDIO
2.0~3.6V VDD1/2
CONTROL INTERFACE
SCLK
XTALI
Copyright © 2011 by Silicon Laboratories
Si4840/44-A10
Si4840/44-A10
2
Rev.1.0
Si4840/44-A10
TABLE O F C ONTENTS
Section
Page
1. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2. Typical Application Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3. Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.2. FM Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
4.3. AM Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
4.4. SW Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.5. Frequency Tuning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.6. Band Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
4.7. Bass and Treble . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
4.8. Volume Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.9. Stereo Audio Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.10. Stereo DAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.11. Soft Mute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.12. Reference Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.13. Memorizing Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.14. Programming with Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5. Commands and Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6. Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.1. Si4840/44-A10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7. Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8. Package Outline: Si4840/44-A10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
9. PCB Land Pattern: Si4840/44-A10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
10. Top Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
10.1. Si4840/44-A10 Top Mark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
11. Additional Reference Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Rev.1.0
3
Si4840/44-A10
1. Electrical Specifications
Table 1. Recommended Operating Conditions1,2
Parameter
Symbol
Supply Voltage3
Power Supply Powerup Rise Time
Test Condition
Min
Typ
Max
Unit
VDD
2
—
3.6
V
VDDRISE
10
—
—
µs
Notes:
1. Typical values in the data sheet apply at VDD = 3.3 V and 25 °C unless otherwise stated.
2. All minimum and maximum specifications in the data sheet apply across the recommended operating conditions for
minimum VDD = 2.7 V.
3. Operation at minimum VDD is guaranteed by characterization when VDD voltage is ramped down to 2.0 V. Part
initialization may become unresponsive below 2.3 V.
Table 2. DC Characteristics
(VDD = 2.7 to 3.6 V, TA = –15 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
—
21.0
—
mA
—
21.5
—
mA
IAM
—
17.0
—
mA
IDDPD
—
10
—
µA
FM Mode
Supply Current1
IFM
Current2
IFM
Supply
Low SNR level
AM/SW Mode
Supply Current1
Supplies and Interface
VDD Powerdown
Current
Notes:
1. Specifications are guaranteed by characterization.
2. LNA is automatically switched to higher current mode for optimum sensitivity in weak signal conditions.
4
Rev.1.0
Si4840/44-A10
Table 3. Reset Timing Characteristics
(VDD = 2.7 to 3.6 V, TA = –15 to 85 °C)
Parameter
RST Pulse Width
Symbol
Min
Typ
Max
Unit
tSRST
100
—
—
µs
tSRST
RST
70%
30%
Figure 1. Reset Timing
Rev.1.0
5
Si4840/44-A10
Table 4. 2-Wire Control Interface Characteristics1,2,3
(VDD = 2.7 to 3.6 V, TA = –15 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
SCLK Frequency
fSCLK
0
—
400
kHz
SCLK Low Time
tLOW
1.3
—
—
µs
SCLK High Time
tHIGH
0.6
—
—
µs
SCLK Input to SDIO  Setup
(START)
tSU:STA
0.6
—
—
µs
SCLK Input to SDIO  Hold
(START)
tHD:STA
0.6
—
—
µs
SDIO Input to SCLK  Setup
tSU:DAT
100
—
—
ns
SDIO Input to SCLK  Hold4,5
tHD:DAT
0
—
900
ns
SCLK input to SDIO  Setup
(STOP)
tSU:STO
0.6
—
—
µs
STOP to START Time
tBUF
1.3
—
—
µs
SDIO Output Fall Time
tf:OUT
—
250
ns
—
300
ns
Cb
20 + 0.1 ----------1pF
SDIO Input, SCLK Rise/Fall Time
tf:IN
tr:IN
Cb
20 + 0.1 ----------1pF
SCLK, SDIO Capacitive Loading
Cb
—
—
50
pF
Input Filter Pulse Suppression
tSP
—
—
50
ns
Notes:
1. When VD = 0 V, SCLK and SDIO are low impedance.
2. When selecting 2-wire mode, the user must ensure that a 2-wire start condition (falling edge of SDIO while SCLK is
high) does not occur within 300 ns before the rising edge of RST.
3. When selecting 2-wire mode, the user must ensure that SCLK is high during the rising edge of RST, and stays high
until after the first start condition.
4. The Si484x delays SDIO by a minimum of 300 ns from the VIH threshold of SCLK to comply with the minimum tHD:DAT
specification.
5. The maximum tHD:DAT has only to be met when fSCLK = 400 kHz. At frequencies below 400 kHz, tHD:DAT may be
violated as long as all other timing parameters are met.
6
Rev.1.0
Si4840/44-A10
SCLK
SDIO
tSU:STA tHD:STA
tLOW
START
tr:IN
tHIGH
tr:IN
tf:IN
tSP
tSU:STO
tBUF
70%
30%
70%
30%
tf:IN,
tf:OUT
tHD:DAT tSU:DAT
STOP
START
Figure 2. 2-Wire Control Interface Read and Write Timing Parameters
SCLK
A6-A0,
R/W
SDIO
START
ADDRESS + R/W
D7-D0
ACK
DATA
D7-D0
ACK
DATA
ACK
STOP
Figure 3. 2-Wire Control Interface Read and Write Timing Diagram
Rev.1.0
7
Si4840/44-A10
Table 5. FM Receiver Characteristics1,2
(VDD = 2.7 to 3.6 V, TA = –15 to 85 °C)
Parameter
Test Condition
Unit
Min
Typ
Max
64
—
109
MHz
—
2.2
—
µV EMF
LNA Input Resistance4,5
—
4
—
k
LNA Input Capacitance4,5
—
5
—
pF
—
50
—
dB
—
105
—
dBµV EMF
Input Frequency
Symbol
fRF
Sensitivity with Headphone
(S+N)/N = 26 dB
Network3
m = 0.3
AM Suppression4,5,6,7
Input IP34,8
Adjacent Channel Selectivity4
±200 kHz
—
50
—
dB
Alternate Channel Selectivity4
±400 kHz
—
65
—
dB
Audio Output Voltage5,6,7,12
—
80
—
mVRMS
Audio Mono S/N5,6,7,9,10
—
55
—
dB
Audio Stereo S/N3,4,5,7,9,10
—
55
—
dB
Audio Frequency Response Low4
–3 dB
—
—
30
Hz
Audio Frequency Response High4
–3 dB
15
—
—
kHz
Audio Stereo Separation5,11
—
40
—
dB
Audio THD5,6,11
—
0.1
0.5
%
Audio Output Load Resistance4,10
RL
Single-ended
10
—
—
k
Audio Output Load Capacitance4,10
CL
Single-ended
—
—
50
pF
—
—
110
ms
Powerup/Band Switch Time4
Notes:
1. Additional testing information is available in “AN603: Si4840/44 DEMO Board Test Procedure.” Volume = maximum
for all tests. Tested at RF = 98.1 MHz.
2. To ensure proper operation and receiver performance, follow the guidelines in “AN602: Si484x-A Antenna, Schematic,
Layout, and Design Guidelines.” Silicon Laboratories will evaluate schematics and layouts for qualified customers.
3. Frequency is 64~109 MHz.
4. Guaranteed by characterization.
5. VEMF = 1 mV.
6. FMOD = 1 kHz, MONO, and L = R unless noted otherwise.
7. f = 22.5 kHz.
8. |f2 – f1| > 2 MHz, f0 = 2 x f1 – f2.
9. BAF = 300 Hz to 15 kHz, A-weighted.
10. At LOUT and ROUT pins.
11. f = 75 kHz.
12. Tested in Digital Volume Mode.
8
Rev.1.0
Si4840/44-A10
Table 6. AM/SW Receiver Characteristics1, 2
(VDD = 2.7 to 3.6 V, TA = –15 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
fRF
Medium Wave (AM)
504
—
1750
kHz
Short Wave (SW)
2.3
—
28.5
MHz
(S+N)/N = 26 dB
—
30
—
µV EMF
Large Signal Voltage Handling5
THD < 8%
—
300
—
mVRMS
Power Supply Rejection Ratio5
∆VDD = 100 mVRMS, 100 Hz
—
40
—
dB
Audio Output Voltage3,6,8
—
60
—
mVRMS
Audio S/N3,4,6
—
55
—
dB
Audio THD3,6
—
0.1
0.5
%
180
—
450
µH
—
—
110
ms
Input Frequency
Sensitivity3,4,5
Antenna Inductance5,7
From powerdown
Powerup/Band Switch Time5
Notes:
1. Additional testing information is available in “AN603: Si4840/44 DEMO Board Test Procedure.” Volume = maximum
for all tests. Tested at RF = 520 kHz.
2. To ensure proper operation and receiver performance, follow the guidelines in “AN602: Si484x-A Antenna, Schematic,
Layout, and Design Guidelines.” Silicon Laboratories will evaluate schematics and layouts for qualified customers.
3. FMOD = 1 kHz, 30% modulation, 2 kHz channel filter.
4. BAF = 300 Hz to 15 kHz, A-weighted.
5. Guaranteed by characterization.
6. VIN = 5 mVrms.
7. Stray capacitance on antenna and board must be < 10 pF to achieve full tuning range at higher inductance levels.
8. Tested in Digital Volume Mode.
Table 7. Reference Clock and Crystal Characteristics
(VDD = 2.7 to 3.6 V, TA = –15 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
—
32.768
—
kHz
–100
—
100
ppm
Crystal Oscillator Frequency
—
32.768
—
kHz
Crystal Frequency Tolerance
–100
—
100
ppm
—
—
3.5
pF
Reference Clock
XTALI Supported Reference Clock
Frequencies
Reference Clock Frequency
Tolerance for XTALI
Crystal Oscillator
Board Capacitance
Rev.1.0
9
Si4840/44-A10
Table 8. Thermal Conditions
Parameter
Symbol
Min
Typ
Max
Unit
Thermal Resistance*
JA
—
80
—
°C/W
Ambient Temperature
TA
–15
25
85
°C
Junction Temperature
TJ
—
—
92
°C
*Note: Thermal resistance assumes a multi-layer PCB with the exposed pad soldered to a topside PCB pad.
Table 9. Absolute Maximum Ratings1,2
Parameter
Symbol
Value
Unit
VDD
–0.5 to 5.8
V
IIN
10
mA
Operating Temperature
TOP
–40 to 95
°C
Storage Temperature
TSTG
–55 to 150
°C
0.4
VPK
Supply Voltage
Input
Current3
RF Input Level4
Notes:
1. Permanent device damage may occur if the above Absolute Maximum Ratings are exceeded. Functional operation
should be restricted to the conditions as specified in the operational sections of this data sheet. Exposure beyond
recommended operating conditions for extended periods may affect device reliability.
2. The Si4840/44-A10 devices are high-performance RF integrated circuits with certain pins having an ESD rating of
< 2 kV HBM. Handling and assembly of these devices should only be done at ESD-protected workstations.
3. For input pins RST, SDIO, SCLK, XTALO, XTALI, BAND, TUNE2, TUNE1, IRQ, and LNA_EN.
4. At RF input pins, FMI, and AMI.
10
Rev.1.0
Si4840/44-A10
2. Typical Application Schematic
TUNE1
B1
TUNE1
2.5k/100M
FMI
(Si4844 only)
R2
253k
S1
VR1
100k
BAND
1
2
AM
BAND
IRQ
FM
1
LNA_EN
3
2
IRQ
TUNE2
TUNE1
4
5
6
NC
R3
180k
To host MCU
LNA_EN
BAND
8
9
7
NC
FMI
RFGND
10
NC
11
AMI
AMI
0.47u
12
C5
NC
ANT1
AM antenna
3
U1
C5
R4
67k
LOUT
Optional
24
ROUT
23
VDD2
DBYP
22
21
XTALI
VDD1
20
19
XTALO
18
SCLK
17
16
RST
15
T1
GND
GND
13
RFGND
14
ANT2
SDIO
AMI
0.47u
LOUT
C4
Optional: AM air loop antenna
C1
0.1u
ROUT
0.1u
VDD
VDD
To host MCU
RESET
SDIO
2.0 TO 3.6V
2.0 TO 3.6V
SCLK
Y1
32.768KHz
C3
22p
C2
22p
Optional
Notes:
1. Place C4 close to VDD2 and DBYP pins.
2. All grounds connect directly to GND plane on PCB.
3. Pin 6 and 7 leave floating.
4. To ensure proper operation and receiver performance, follow the guidelines in “AN602: Si484x-A Antenna, Schematic,
Layout, and Design Guidelines.” Silicon Labs will evaluate the schematics and layouts for qualified customers.
5. Pin 8 connects to the FM antenna interface and pin 12 connects to the AM antenna interface.
6. Place Si484x as close as possible to antenna jack and keep the FMI and AMI traces as short as possible.
Rev.1.0
11
Si4840/44-A10
3. Bill of Materials
Table 10. Si4840/44-A10 Bill of Materials
Component(s)
Value/Description
Supplier
C1
Reset capacitor 0.1 µF, ±20%, Z5U/X7R
Murata
C4
Supply bypass capacitor, 0.1 µF, ±20%, Z5U/X7R
Murata
C5
Coupling capacitor, 0.47 µF, ±20%, Z5U/X7R
Murata
B1
Ferrite bead 2.5 k/100 MHz
Murata
Variable resistor (POT), 100 k, ±10% 
Kennon
VR1
U1
ANT1
Si484x AM/FM/SW Analog Tune Digital Display Radio Tuner
Ferrite stick,180–450 μH
Silicon Laboratories
Jiaxin
Optional Components
C2, C3
Y1
ANT2
12
Crystal load capacitors, 22 pF, ±5%, COG
(Optional: for crystal oscillator option)
32.768 kHz crystal (Optional: for crystal oscillator option)
Venkel
Epson or equivalent
various
Air loop antenna, 10-20 μH
S1
Band switch
Any, depends on customer
R2
Resistor, 253 k, ±1%,
Venkel
R3
Resistor, 180 k, ±1%
Venkel
R4
Resistor, 67 k, ±1%
Venkel
Rev.1.0
Si4840/44-A10
4. Functional Description
Si484x
Si4830/34
ADC
AMI
AM
ANT
RFGND
LNA
FMI
LOUT
DAC
ROUT
DSP
ADC
FM
ANT
DAC
AGC
0/90
TUNE1/2
ADC
AFC
BAND
RST
XTAL
OSC
IRQ
REG
SDIO
2.0~3.6V VDD1/2
CONTROL INTERFACE
SCLK
XTALI
Figure 4. Si4840/44-A10 Functional Block Diagram
4.1. Overview
The Si4840/44-A10 is the first analog-tuned digitaldisplay digital CMOS AM/FM/SW radio receiver IC that
integrates the complete receiver function from antenna
input to audio output. Working with an external MCU
with LCD/LED driver, Si4840/44-A10 can output the
AM/FM/SW frequencies, band, Bass/Treble and
stereo/mono information to display on LCD/LED, while
using a simple potentiometer at the front end for analogtune. Leveraging Silicon Laboratories' proven and
patented digital low intermediate frequency (low-IF)
receiver architecture, the Si4840/44 delivers superior
RF performance and interference rejection in AM, FM
and SW bands. Additionally, the digital core provides
advanced audio conditioning for all environments,
removing pops, clicks, and loud static in variable signal
conditions. The superior control algorithm integrated in
Si4840/44-A10 provides easy and reliable control
interface while eliminating all the manual tuned external
components used in traditional solutions.
Like other successful audio products from Silicon Labs,
Si4840/44-A10 offers unmatched integration and PCB
space savings with minimum external components and
small board area on a single side PCB. The high
integration and complete system production test
simplifies design-in, increases system quality, and
improves manufacturability. The receiver has very low
power consumption, runs off two AAA batteries, and
delivers the performance benefits of high performance
digital radio experience with digital display to the legacy
analog-tuned radio market.
The Si4840/44-A10 provides good flexibility in using the
chip. The frequency range of FM/AM/SW bands,
mono/stereo threshold, de-emphasis value, AM tuning
step, AM soft mute level/rate, and Bass/Treble can be
either configured by the MCU or by using external
hardware to make a selection. The reference clock of
the FM tuner can be either provided by the crystal, or by
the host MCU within tolerance.
Si4840/44-A10 also has flexibility in selecting bands
and configuring band properties, enabling masked Host
MCU for multiple projects, and reducing the cost of
development. Four tuning preferences are available to
meet different tuning preference requirements.
Rev.1.0
13
Si4840/44-A10
4.2. FM Receiver
The Si4840/44-A10 integrates a low noise amplifier
(LNA) supporting the worldwide FM broadcast band (64
to 109 MHz).
Pre-emphasis and de-emphasis is a technique used by
FM broadcasters to improve the signal-to-noise ratio of
FM receivers by reducing the effects of high frequency
interference and noise. When the FM signal is
transmitted, a pre-emphasis filter is applied to
accentuate the high audio frequencies. All FM receivers
incorporate a de-emphasis filter which attenuates high
frequencies to restore a flat frequency response. Two
time constants are used in various regions. The deemphasis time constant can be chosen to be 50 or
75 μs. Refer to "AN602: Si484x-A Antenna, Schematic,
Layout, and Design Guidelines."
The Si4840/44-A10 also has advanced stereo blending
that employs adaptive noise suppression. As a signal
quality degrades, the Si4840/44-A10 gradually
combines the stereo left and right audio channels to a
mono audio signal to maintain optimum sound fidelity
under varying reception conditions. The Si4840/44-A10
can output a stereo signal to MCU with LCD/LED driver
to display on the LCD/LED so that the user can easily
discern the signal quality.
To offer maximum flexibility, the receiver supports a
wide range of ferrite loop sticks from 180–450 μH. An
air loop antenna is supported by using a transformer to
increase the effective inductance from the air loop.
Using a 1:5 turn ratio inductor, the inductance is
increased by 25 times and easily supports all typical AM
air loop antennas, which generally vary between 10 and
20 μH.
A 9, 10 kHz tuning step can be chosen by the external
resistor or host MCU according to the different regions,
and AM soft mute level can be programmed by the host
MCU to have different tuning experiences. Refer to
“AN610: Si484x-A Programming Guide” and "AN602:
Si484x-A Antenna, Schematic, Layout, and Design
Guidelines" for more details.
4.4. SW Receiver
The Si4844 supports short wave band receptions from
2.3 to 28.5 MHz in 5 kHz step size increments. Si4844
supports extensive short wave features such as minimal
discrete components and no factory adjustments. The
Si4844 supports using the FM antenna to capture short
wave signals. Refer to “AN610: Si484x-A Programming
Guide” and "AN602: Si484x-A Antenna, Schematic,
Layout, and Design Guidelines."for more details.
The stereo on signal is defined using both RSSI and the
Left and Right separation levels as these two
specifications are the primary factors for stereo
listening. The criteria can be set between two
conditions: the Left and Right channels are separated
by more than 6 dB with RSSI at >20 dB or Left and
Right channels are separated by more than 12 dB with
RSSI at >28 dB. The selection can be set up using
different values of the external resistor or configured by
the host MCU. Refer to "AN602: Si484x-A Antenna,
Schematic, Layout, and Design Guidelines." The user
can also refer to the “AN610: Si484x-A Programming
Guide” for those who want to configure the value by
host MCU.
4.5. Frequency Tuning
4.3. AM Receiver
4.6. Band Select
The highly integrated Si4840/44-A10 supports
worldwide AM band reception from 504 to 1750 kHz
with five sub-bands using a digital low-IF architecture
with a minimum number of external components and no
manual alignment required. This patented architecture
allows for high-precision filtering, offering excellent
selectivity and SNR with minimum variation across the
AM band. Similar to the FM receiver, the Si4840/44-A10
optimizes sensitivity and rejection of strong interferers,
allowing better reception of weak stations.
The Si4840/44-A10 supports worldwide AM band with
five sub-bands, US/Europe/Japan/China FM band with
five sub-bands, and SW band with 16 sub-bands.
Si4840/44-A10 provides the flexibility to configure the
band and band properties at either the MCU side or the
Tuner side, enabling masked MCU for multiple projects.
For details on band selection, refer to "AN602: Si484x-A
Antenna, Schematic, Layout, and Design Guidelines"
and "AN610: Si484x-A Programming Guide".
14
A valid channel can be found by tuning
potentiometer that is connected to the TUNE1 and
the
TUNE2 pin of the Si4840/44-A10 chip.
To offer easy tuning, the Si4840/44-A10 also outputs the
tuned information to the MCU with LCD/LED driver to
display. It will light up the icon on display if the RF signal
quality passes a certain threshold when tuned to a valid
station. Four tuning preferences are available. The user
can choose to have the best performance (volume,
stereo/mono effect) only at the exact channel, or the
best performance in a larger range. Refer to "AN610:
Si484x-A Programming Guide" for more details.
Rev.1.0
Si4840/44-A10
4.7. Bass and Treble
4.9.2. Stereo-Mono Blending
The Si4840/44-A10 further supports Bass/Treble tone
control for superior sound quality. The Si4840/44-A10
can be set to be default normal, or programmed by the
host MCU I2C-compatible 2-wire mode. FM has nine
levels Bass/Treble effect and AM/SW has seven levels
Bass/Treble effect.For further configuration details, refer
to "AN610: Si484x-A Programming Guide."
Adaptive noise suppression is employed to gradually
combine the stereo left and right audio channels to a
mono (L+R) audio signal as the signal quality degrades
to maintain optimum sound fidelity under varying
reception conditions. Three metrics, received signal
strength indicator (RSSI), signal-to-noise ratio (SNR),
and
multipath
interference,
are
monitored
simultaneously in forcing a blend from stereo to mono.
The metric which reflects the minimum signal quality
takes precedence and the signal is blended
appropriately.
4.8. Volume Control
The Si4840/44-A10 not only allows users to use the
traditional PVR wheel volume control through an
external speaker amplifier, it also supports digital
volume control programmed by the host MCU.
Si4840/44-A10 can be programmed to be Bass/Treble
mode only or digital volume mode only; it can also be
programmed to have the digital volume coexist with
Bass/Treble in two modes. Refer to "AN610: Si484x-A
Programming Guide" and "AN602: Si484x-A Antenna,
Schematic, Layout, and Design Guidelines" for more
details.
4.9. Stereo Audio Processing
Modulation Level
The output of the FM demodulator is a stereo
multiplexed (MPX) signal. The MPX standard was
developed in 1961, and is used worldwide. Today's
MPX signal format consists of left + right (L+R) audio,
left – right (L–R) audio, a 19 kHz pilot tone.
Mono Audio
Left + Right
0
Stereo
Pilot
15 19 23
Stereo Audio
Left - Right
38
4.10. Stereo DAC
High-fidelity stereo digital-to-analog converters (DACs)
drive analog audio signals onto the LOUT and ROUT
pins. The audio output may be muted.
4.11. Soft Mute
The soft mute feature is available to attenuate the audio
outputs and minimize audible noise in very weak signal
conditions. Advanced algorithm is implemented to get a
better analog tuning experience. The soft mute feature
is triggered by the SNR metric. The SNR threshold for
activating soft mute is programmable, as are soft mute
attenuation levels and attack and decay rates.
RDS/
RBDS
53
All three metrics have programmable stereo/mono
thresholds and attack/release rates. If a metric falls
below its mono threshold, the signal is blended from
stereo to full mono. If all metrics are above their
respective stereo thresholds, then no action is taken to
blend the signal. If a metric falls between its mono and
stereo thresholds, then the signal is blended to the level
proportional to the metric’s value between its mono and
stereo thresholds, with an associated attack and
release rate.
57
4.12. Reference Clock
Frequency (kHz)
The Si4840/44-A10 supports RCLK input (to XTALI pin)
with the spec listed in Table 7. It can be shared with the
host MCU to save extra crystal.
Figure 5. MPX Signal Spectrum
4.9.1. Stereo Decoder
The Si4840/44-A10's integrated stereo decoder
automatically decodes the MPX signal using DSP
techniques. The 0 to 15 kHz (L+R) signal is the mono
output of the FM tuner. Stereo is generated from the
(L+R), (L–R), and a 19 kHz pilot tone. The pilot tone is
used as a reference to recover the (L–R) signal. Output
left and right channels are obtained by adding and
subtracting the (L+R) and (L–R) signals respectively.
An onboard crystal oscillator is available to generate the
32.768 kHz reference when an external crystal and
load capacitors are provided. Refer to "AN602: Si484xA Antenna, Schematic, Layout, and Design Guidelines"
for more details.
4.13. Memorizing Status
The Si4840/44-A10 provides the feature to memorize
status from the last power down with a simple design on
PCB, including frequency of the FM/AM/SW station.
Refer to "AN602: Si484x-A Antenna, Schematic,
Layout, and Design Guidelines" for details.
Rev.1.0
15
Si4840/44-A10
4.14. Programming with Commands
To ease development time and offer maximum
customization, the Si484x provides a simple yet
powerful software interface to program the receiver. The
device is programmed using commands, arguments,
properties, and responses.
To perform an action, the user writes a command byte
and associated arguments, causing the chip to execute
the given command. Commands control an action such
as powerup the device, shut down the device, or get the
current tuned frequency. Arguments are specific to a
given command and are used to modify the command.
Properties are a special command argument used to
modify the default chip operation and are generally
configured immediately after powerup. Examples of
properties are de-emphasis level, RSSI seek threshold,
and soft mute attenuation threshold.
Responses provide the user information and are
echoed after a command and associated arguments are
issued. All commands provide a 1-byte status update,
indicating interrupt and clear-to-send status information.
For a detailed description of the commands and
properties for the Si484x, see "AN610: Si484x-A
Programming Guide".
Rev.1.0
16
Si4840/44-A10
5. Commands and Properties
Table 11. Si4840/44-A10 FM Receiver Command Summary
Cmd
Name
Description
0xE0
ATDD_GET_STATUS
0xE1
ATDD_POWER_UP
0xE2
ATDD_AUDIO_MODE
0x10
GET_REV
0x11
POWER_DOWN
Power down device.
0x12
SET_PROPERTY
Sets the value of a property.
0x13
GET_PROPERTY
Retrieve a property's value.
Get tune freq, band and etc status of the device
Power up device, band selection and band properties setup
Audio output mode: get/set audio mode and settings
Returns the revision information of the device.
Note: The si4840/44 has its own power up and get status commands which is different from previous si47xx tuner parts. To
differentiate, we use “ATDD_POWER_UP” and ATDD_GET_STATUS to denote the ATDD specific commands instead
of the general si47xx “POWER_UP” and “STATUS” commands
Table 12. Si4840/44-A10 FM Receiver Property Summary
Prop
Name
0x1100
FM_DEEMPHASIS
0x1300
FM_SOFT_MUTE_RATE
0x1301
Description
Default
Sets deemphasis time constant. Default is 75 μs.
0x0002
Sets the attack and decay rates when entering and leaving
soft mute.
0x0040
FM_SOFT_MUTE_SLOPE
Configures attenuation slope during soft mute in dB attenuation per dB SNR below the soft mute SNR threshold. Default
value is 2.
0x0002
0x1302
FM_SOFT_MUTE_
MAX_ATTENUATION
Sets maximum attenuation during soft mute (dB). Set to 0 to
disable soft mute. Default is 16 dB.
0x0010
0x1303
FM_SOFT_MUTE_
SNR_THRESHOLD
Sets SNR threshold to engage soft mute. Default is 4 dB.
0x0004
0x1207
FM_STEREO_IND
_BLEND_THRESHOLD
Sets the blend threshold for stereo indicator. Default value is
band dependent (either 0x9F or 0xB2)
0x9F
0xB2
0x1800
FM_BLEND_RSSI_
STEREO_THRESHOLD
Sets RSSI threshold for stereo blend. (Full stereo above
threshold, blend below threshold.) To force stereo, set this to
0. To force mono, set this to 127. Default value is 49 dBμV.
0x0031
0x1801
FM_BLEND_RSSI_
MONO_THRESHOLD
Sets RSSI threshold for mono blend (Full mono below
threshold, blend above threshold). To force stereo, set this to
0. To force mono, set this to 127. Default value is band
dependent (either 8 or 7).
0x0008
0x0007
0x4000
RX_VOLUME
Sets the output volume.
0x003F
0x4001
RX_HARD_MUTE
Mutes the audio output. L and R audio outputs may be
muted independently.
0x0000
0x4002
RX_BASS_TREBLE
Sets the output bass/treble level
0x0004
0x4003
RX_ACTUAL_VOLUME
Read the actual output volume
0x003F
Rev.1.0
17
Si4840/44-A10
Table 13. Si4840/44-A10 AM/SW Receiver Command Summary
Cmd
Name
Description
0xE0
ATDD_GET_STATUS
0xE1
ATDD_POWER_UP
0xE2
ATDD_AUDIO_MODE
0x10
GET_REV
0x11
POWER_DOWN
Power down device.
0x12
SET_PROPERTY
Sets the value of a property.
0x13
GET_PROPERTY
Retrieve a property's value.
Get tune freq, band and etc status of the device
Power up device, band selection and band properties setup
Audio output mode: get/set audio mode settings.
Returns the revision information of the device.
Note: The si4840/44 has its own power up and get status commands which is different from previous si47xx tuner parts. To
differentiate, we use “ATDD_POWER_UP” and ATDD_GET_STATUS to denote the ATDD specific commands instead
of the general Si47xx “POWER_UP” and “STATUS” commands.
Table 14. Si4840/44-A10 AM/SW Receiver Property Summary
Prop
Name
0x4000
RX_VOLUME
0x4001
RX_HARD_MUTE
0x4002
RX_BASS_TREBLE
0x4003
Description
Default
Sets the output volume.
0x003F
Mutes the audio output. L and R audio outputs may be
muted independently.
0x0000
Sets the output bass/treble level
0x0003
RX_ACTUAL_VOLUME
Read the actual output volume
0x003F
0x3300
AM_SOFT_MUTE_RATE
Sets the attack and decay rates when entering and leaving
soft mute.
0x0040
0x3301
AM_SOFT_MUTE_SLOPE
Configures attenuation slope during soft mute in dB attenuation per dB SNR below the soft mute SNR threshold.
0x0002
0x3302
AM_SOFT_MUTE_
MAX_ATTENUATION
Sets maximum attenuation during soft mute (dB). Set to 0
to disable soft mute.
0x0010
0x3303
AM_SOFT_MUTE_
SNR_THRESHOLD
Sets SNR threshold to engage soft mute.
0x0008
18
Rev.1.0
Si4840/44-A10
6. Pin Descriptions
6.1. Si4840/44-A10
LNA_EN
1
24
LOUT
IRQ
2
23
ROUT
TUNE1
3
22
DBYP
TUNE2
4
21
VDD2
BAND
5
20
VDD1
NC
6
19
XTALI
NC
7
18
XTALO
FMI
8
17
SCLK
RFGND
9
16
SDIO
NC
10
15
RST
NC
11
14
GND
AMI
12
13
GND
Pin Number(s)
Name
Description
1
LNA_EN
2
IRQ
Interrupt Request
3
TUNE1
Frequency tuning
4
TUNE2
Frequency tuning
5
BAND
Band selection and De-emphasis/Stereo separation selection
6,7
NC
No connect. Leave floating.
8
FMI
FM RF inputs. FMI should be connected to the antenna trace.
9
RFGND
10, 11
NC
Unused. Tie these pins to GND.
12
AMI
AM RF input. AMI should be connected to the AM antenna.
13, 14
GND
Ground. Connect to ground plane on PCB.
15
/RST
Device reset (active low) input
16
SDIO
Serial data input/output
17
SCLK
Serial clock input
18
XTALO
Crystal oscillator output
19
XTALI
Crystal oscillator input
20
VDD1
Supply voltage. May be connected directly to battery.
21
VDD2
Supply voltage. May be connected directly to battery.
22
DBYP
Dedicated bypass for VDD
23
ROUT
Right audio line output in analog output mode
24
LOUT
Left audio line output in analog output mode
Enabling SW external LNA
RF ground. Connect to ground plane on PCB.
Rev.1.0
19
Si4840/44-A10
7. Ordering Guide
Part Number*
Description
Package Type
Operating
Temperature/Voltage
Si4840-A10-GU
AM/FM Broadcast Radio Receiver
24L SSOP Pb-free
–15 to 85 °C
2.0 to 3.6 V
Si4844-A10-GU
AM/FM/SW Broadcast Radio Receiver
24L SSOP Pb-free
–15 to 85 °C
2.0 to 3.6 V
*Note: Add an “(R)” at the end of the device part number to denote tape and reel option. The devices will typically operate at
25 °C with degraded specifications for VDD voltage ramped down to 2.0 V.
20
Rev.1.0
Si4840/44-A10
8. Package Outline: Si4840/44-A10
The 24-pin SSOP illustrates the package details for the Si4840/44-A10. Table 15 lists the values for the dimensions
shown in the illustration.
Figure 6. 24-Pin SSOP
Table 15. Package Dimensions
Dimension
A
A1
b
c
D
E
E1
e
L
θ
aaa
bbb
ccc
ddd
Min
—
0.10
0.20
0.10
Nom
—
—
—
—
8.65 BSC
6.00 BSC
3.90 BSC
0.635 BSC
—
—
0.20
0.18
0.10
0.10
0.40
0°
Max
1.75
0.25
0.30
0.25
1.27
8°
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to the JEDEC Solid State Outline MO-137, Variation AE.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification
for Small Body Components.
Rev.1.0
21
Si4840/44-A10
9. PCB Land Pattern: Si4840/44-A10
Figure 7 illustrates the PCB land pattern details for the Si4840/44-A10-GU SSOP. Table 16 lists the values for the
dimensions shown in the illustration.
Figure 7. PCB Land Pattern
Table 16. PCB Land Pattern Dimensions
Dimension
Min
C
5.20
E
Max
5.40
0.635 BSC
X1
0.35
0.45
Y1
1.55
1.75
General:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. This land pattern design is based on the IPC-7351 guidelines.
Solder Mask Design:
3. All metal pads are to be non-solder mask defined (NSMD). Clearance between the
solder mask and the metal pad is to be 60 µm minimum, all the way around the pad.
Stencil Design:
4. A stainless steel, laser-cut, and electro-polished stencil with trapezoidal walls
should be used to assure good solder paste release.
5. The stencil thickness should be 0.125 mm (5 mils).
6. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads.
Card Assembly:
7. A No-Clean, Type-3 solder paste is recommended.
8. The recommended card reflow profile is per the JEDEC/IPC J-STD-020
specification for Small Body Components.
22
Rev.1.0
Si4840/44-A10
10. Top Markings
10.1. Si4840/44-A10 Top Mark
4840A10GU
YYWWTTTTTT
4844A10GU
YYWWTTTTTT
Mark Method:
YAG Laser
Line 1 Marking:
Device identifier
Line 2 Marking:
YY = Year
WW = Work week
Assigned by the Assembly House.
TTTTTT = Manufacturing code
4840A10GU = Si4840-A10
4844A10GU = Si4844-A10
Rev.1.0
23
Si4840/44-A10
11. Additional Reference Resources
Contact your local sales representatives for more information or to obtain copies of the following references:
EN55020 Compliance Test Certificate
AN602: Si484x-A Antenna, Schematic, Layout, and Design Guidelines
 AN603: Si4840/44-DEMO Board Test Procedure
 Si4840/44-DEMO Board User’s Guide
 AN610: Si484x-A Programming Guide


24
Rev.1.0
Si4840/44-A10
DOCUMENT CHANGE LIST
Revision 0.4 to Revision 1.0


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


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Updated Block Diagram
Updated Table 3 “Reset Timing Characteristics” and
Figure 1, “Reset Timing,”
Updated Table 5, “FM Receiver Characteristics”
Updated Table 8, “Thermal Conditions”
Updated Table 9, "Absolute Maximum Ratings"
Updated Section “2. Typical Application Schematic ”
Updated Section “3. Bill of Materials ”
Updated Section “4.7. Bass and Treble”
Removed previous Section “4.10. Received Signal
Qualifiers”
Updated Section “4.13. Memorizing Status”
Updated Section “4.14. Programming with
Commands”
Updated Table 13, “Si4840/44-A10 AM/SW Receiver
Command Summary”
Updated Table 16, “PCB Land Pattern Dimensions”
Rev.1.0
25
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